Entwicklung eines schnellen Bio-Tests zur Untersuchung des Wirkungs-potentials von mikrobiellen Pflanzenstärkungsmitteln

Plant-growth-promoting soil microorganisms are increasingly distributed on the world market. Nutrient mobilization, stimulation of root growth, enhanced resistance to envi-ronmental stress factors are discussed as possible mechanisms. These assumptions are based only on scarce scientific evidence due to limited reproducibility of pot and field experiments, limited information concerning the conditions for successful applica-tion, limited standardization of inoculum preparation and quality. Thus, the develop-ment of rapid screening tests is to demonstrate the principle effectiveness of biofertil-izers prior to set-up of labourous pot or field experiments is urgently required. In this study, a rapid bio-test with cucumber (Cucumis sativa L.) as an indicator plant was developed to evaluate the effectiveness of five commercial biofertilizers based on Trichoderma spp. and Bacillus spp. (Biohealth-G, Biohealth-WSG, Biomex, Vitalin T50 and SP11) using germination rate, root and shoot biomass, maximum root length, and leaf area as test parameters. The experiment was repeated twice with 6 replicates in hydroponic culture under controlled conditions (pH 5.5, 22° C; Light: 230 mmol cm2 sec-1). Biofertilizers were applied at the rate of 3 g per 2.5 l mineral nutrient solution. Germination rate was increased by 20 - 25% in all biofertilizer treatments compared to the control. After 2 weeks culture period, root dry weight and leaf area of Biohealth-G, Vitalin T50, SP-11 and Biomex-treated cucumber seedlings were significantly in-creased. Biohealth-G and Vitalin T50 showed significantly higher main root length and Biohealth-G higher shoot dry weight than the remaining treatments, while Biohealth-WSG did not cause differences compared to untreated control plants. The pathogen-antagonistic potential of Trichoderma strains can be easily tested by co-inoculation with the pathogenic fungus Gaeumannomyces graminis on malt extract peptone agar plates. The results suggest that the activity potential of different Trichoderma-based biofertilizers could be easily screened by using the described bio-test with cucumber seedlings

Nitrogen use efficiency of irrigated dry bean (Phaseolus vulgaris L.) genotypes in southern Alberta

Although dry bean (Phaseolus vulgaris L.) is a legume capable of fixing nitrogen, fertilizer N is usually recommended for its production in Canada because it is believed to be an inefficient N fixer. Using genotypes with high N use efficiency (NUE) would reduce the amount of applied N, which usually has deleterious environmental effects. We evaluated 22 bean genotypes for N uptake efficiency (NUpE) in a greenhouse trial, and 16 genotypes for N use efficiency (NUE) and its components: NUpE and N utilization efficiency (NUtE) in two seasons (2012 and 2013) of a field trial at 30 kg N ha-1 (30N) and 100 kg N ha-1 (100N) soil levels. Root biomass and surface area were highly correlated with NUpE in the greenhouse, where NUpE at 100N was 48% lower than that at 30N. In the field trial, grain yield was highly correlated with NUpE and NUtE at both 30N and 100N. The NUpE at 100N was 65% lower than that at 30N, and NUE at 100N was 68% lower than that at 30N. The low NUE at 100N in the field trial was mainly due to the difference in NUpE. This study also identified nine genotypes including five germplasm lines (PI 136692, GH-196, UNS-117, UI-239 and LEF2RB) and four cultivars (Othello, Viva, AC Redbond and Island) that were both N-efficient (at 30N) and N-responsive (to 100N).The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Biological nitrogen fixation by irrigated dry bean (Phaseolus vulgaris L.) genotypes

Dry bean (Phaseolus vulgaris L.) is usually considered to be poor at biological nitrogen fixation (BNF), but large variations in this trait have been observed among bean genotypes. We evaluated 16 bean genotypes for N2 fixation ability in four N treatments: (a) uninoculated in low-N soil (30 kg N ha-1), (b) inoculated with commercial Rhizobium leguminosarum bv. phaseoli inoculant Nitrastik-DÂŽ in low-N soil, (c) inoculated with commercial R. leguminosarum bv. phaseoli inoculant NodulatorÂŽ in low-N soil, and (d) uninoculated in high-N soil (100 kg N ha-1). There were differences between genotypes in all the plant parameters that were measured, but only nodulation was affected by N treatment. The 100 kg N ha-1 treatment suppressed nodulation. Seven genotypes nodulated well with either inoculant, two genotypes nodulated better with Nitrastik-D than with Nodulator, three nodulated better with Nodulator than with Nitrastik-D, and four nodulated poorly with either inoculant. Cultivars AC Redbond, Island and Resolute, all currently commercially grown, did not fix much N2 measured at flowering (4-8 kg N ha-1) or maturity (19-34 kg N ha-1). By contrast, germplasm lines PI 136692 (red bean), GH-196 (pinto bean) and LEF2RB (carioca bean) had high BNF capability at flowering (10-11 kg N ha-1) and especially at maturity (60-72 kg N ha-1), in addition to high seed yield (2778-2897 kg ha-1), indicating their superior ability to support both of these economically important traits throughout plant growth. These three genotypes would be valuable to breeders for genetic improvement of BNF in dry bean cultivars.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author